Tyre Sizing Guide
Tyre Sizing Help
Your tyre size can be found on the side-wall of the tyre.
Sizes are made up of many different combinations including various numbers and letters.
For example, 185/55R16 100V:
- 185 represents the tyre section width in millimetres (the width of the treaded area)
- 55 represents the aspect ratio (side-wall height). The number is a percentage of the tyre width.
- R denotes the tyre’s construction type. In this case, Radial.
- 16 is the diameter of the wheel in inches.
- 100 is this tyre’s load index.
- V is the speed rating for this tyre.
Load Index
The load index is a code showing the maximum load a tyre can carry at the speed indicated by its speed symbol.
You will find your load rating as shown: 185/55R16 100 V
| Load Index | Max. Load (kg) | Load Index | Max. Load (kg) | Load Index | Max. Load (kg) | Load Index | Max. Load (kg) | Load Index | Max. Load (kg) | Load Index | Max. Load (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 60 | 250 | 71 | 345 | 82 | 475 | 93 | 650 | 104 | 900 | 115 | 1,215 |
| 61 | 257 | 72 | 355 | 83 | 487 | 94 | 670 | 105 | 925 | 116 | 1,250 |
| 62 | 265 | 73 | 365 | 84 | 500 | 95 | 690 | 106 | 950 | 117 | 1,285 |
| 63 | 272 | 74 | 375 | 85 | 515 | 96 | 710 | 107 | 975 | 118 | 1,320 |
| 64 | 280 | 75 | 387 | 86 | 530 | 97 | 730 | 108 | 1,000 | 119 | 1,360 |
| 65 | 290 | 76 | 400 | 87 | 545 | 98 | 750 | 109 | 1,030 | 120 | 1,400 |
| 66 | 300 | 77 | 412 | 88 | 560 | 99 | 775 | 110 | 1,060 | 121 | 1,450 |
| 67 | 307 | 78 | 425 | 89 | 580 | 100 | 800 | 111 | 1,090 | 122 | 1,500 |
| 68 | 315 | 79 | 437 | 90 | 600 | 101 | 825 | 112 | 1,120 | 123 | 1,550 |
| 69 | 325 | 80 | 450 | 91 | 615 | 102 | 850 | 113 | 1,150 | 124 | 1,600 |
| 70 | 335 | 81 | 462 | 92 | 630 | 103 | 875 | 114 | 1,180 | 125 | 1,650 |
Speed Rating
The speed rating represents the maximum permissible speed for which the tyre is rated.
You will find your speed rating as shown: 185/55/R16 100 V
| Rating | Max Speed | Rating | Max Speed |
| N | 87mph | H | 130mph |
| P | 93mph | V | 149mph |
| Q | 99mph | Z | 150+mph |
| R | 106mph | W | 168mph |
| S | 112mph | Y | 186mph |
| T | 118mph | Above | Call for specialist applications |
| U | 124mph |
You should replace your tyres with those of the same size, load and speed rating as recommended by the vehicles’ manufacturer.Increasing the value of both the load and/or speed rating is acceptable practice but it is not recommended that lower value products be fitted.
There is currently no legal requirement for speed ratings but it is advised to check with your vehicle insurer of any potential issues that may arise when significantly altering specifications.
If you require any further information in respect of these issues, please do feel free to give us a call – we will be happy to check all the technical requirements of your specific vehicle (where available).
Further Tyre Information
As well as the size, speed and load rating there is further information available to you when selecting the right products for your vehicle online. Certain vehicle manufacturers work very closely with tyre manufacturers to create a particular product which best suits a given vehicle. Mercedes, for example, may select CONTINENTAL tyres as original equipment for a particular model. These tyres would have been developed by CONTINENTAL to deliver the best overall performance for that specific model. The tyre will then be branded with an ‘MO’ classification and provided as an after-market product for you to buy when the original tyres become worn out or damaged.
It is not absolutely necessary to purchase a tyre classified in this way, and indeed an MO tyre, for example, could also be fitted to other models and makes of vehicle without issue – it is simply that these products may best suit that make of vehicle…….
N-Rated Porsche Tyres
Original Equipment Porsche tyres have to undergo considerable lab tests in order to prove beyond doubt that they would be able to perform underneath a Porsche running at top speed in both dry and wet weather conditions. Following this work, they are produced and handed over to ever-stringent Porsche engineers to test them to the extreme. If all testing is approved and passed, Porsche will officially approve the tyres for OE fitment on each new model. For every revision, the tyre is reclassified with a new ‘N’ rating. The process begins with N0 and runs through sequentially to N4 as developments are implemented.
Porsche recommend that only tyres of the same make, model and N rating are fitted to thier vehicles. While it is possible to buy exactly the same looking tyre in exactly the same size and speed/load rating – it is not the optimum product and the car should be driven accordingly….
Other Tyre Manufacturer Related Coding
Tyres developed and denoted as Original Equipment by manufacturers carry additional coding for identification:
| CODE | MANUFACTURER | CODE | MANUFACTURER |
|---|---|---|---|
| ( – ) or – | Peugeot / Volvo | LOTUS | Lotus |
| ( * ) or * | BMW / Fiat | M | Maserati |
| ( 1 ) or 1 | Bentley / Maserati | M0 / MO | Mercedes |
| 1Z | Toyota | M3 | BMW M3 |
| 5Z | Ford | MB | Mercedes |
| ( a ) or a | Audi / Seat / Volvo / VW | MZ | Mitsubishi / Toyota |
| ( A ) or A | Alfa Romeo | N0 | Porsche v.1 |
| AU | Audi | N1 | Porsche v.2 |
| AZ | Alfa / Fiat / Subaru / Toyota | N2 | Porsche v.3 |
| B | BMW | N3 | Porsche v.4 |
| BM | BMW | N4 | Porsche v.5 |
| BZ | Audi / Honda / Mazda / MercedesOpel / Skoda / VW | (P) of P | Peugeot / Porsche |
| C1 | Chrysler / Daimler / Dodge | PZ | Ford / Mazda / Mercedes / VW |
| CZ | Subaru | R | Renault |
| DC | Chrysler / Daimler | RE | Renault |
| DZ | Honda / Mazda / Toyota | RU | BMW / Ferrari / Lexus / Mercedes |
| EZ | Audi / Mazda 6 | SMART | Smart |
| (f) or f | Fiat | SZ | Mazda MPV |
| (F) of F | Ferrari / Ford | TZ | Mazda 6 |
| FE | Ferrari | UV | VolksWagen |
| FO | Ford | UZ | BMW 3 Series / Skoda |
| G1 | Mercedes | Volvo | Volvo |
| GZ | Subaru | VW | VolksWagen |
| (J) or J | Jaguar | VW Golf 3 | VW Golf mk3 |
| JZ | Seat / Subaru | VW Golf 4 | VW Golf mk4 |
| L | Lexus | XZ | Nissan |
| LZ | Lancia | YZ | Hyundai / Kia / Mazda / Mercedes |
| K1 | Ferrari | Z | Mazda / Toyota |
| KZ | Nissan / Toyota | R01 | Audi |